Biology subjects

Cragg, M.

Publications and source records attributed to Cragg, M..

5 recordsLinked to original sources

bioRxiv2026

Patient-derived monoclonal anti-HPA-1a can induce platelet activation through FcγRIIa

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a pregnancy-associated disorder caused by maternal alloantibodies targeting paternally inherited human platelet antigens (HPAs). These antibodies traverse the placenta and bind to fetal platelets, causing thrombocytopenia and potentially severe complications including intracranial hemorrhage (ICH). Beyond platelets, antibodies may also target other fetal cells such as endothelial cells and placental trophoblasts thereby exacerbating disease severity. Anti-HPA-1a antibodies, the primary cause of FNAIT, display functional heterogeneity due to differences in epitope specificity, glycosylation, which complicate disease severity prediction. Here, we report the structural and functional characterization of two novel anti-HPA-1a antibodies, D-204 and M-204, derived from a mother with a severe FNAIT case. In comparison to D-204 and other existing anti-HPA-1a antibodies such as B2G1 and 26.4, M-204 bound IIb{beta}3 with different kinetics, reaching only half-maximal binding, as determined by flow cytometry. Notably, only M-204 induced platelet aggregation. To investigate the underlying mechanism behind this aggregation, various antibody formats were generated (Fab, Fab2, bispecific, and IgG-Fc dead). Aggregation required both Fab-arms to engage HPA-1a and intact binding to Fc{gamma}RIIa. Structural models and crystal structures suggest the dual engagement of both Fab-arms is required for Fc{gamma}RIIA-engagement which is a unique feature of M-204 among known HPA-1 monoclonals. Our findings highlight the functional diversity of anti-HPA-1a antibodies and provide new insights into their pathogenic mechanisms.

immunology↗

bioRxiv2026

Rheumatoid Arthritis-associated IgG N-glycan agalactosylation diminishes neutrophilic inflammation by reducing FcgammaR binding and downstream signaling

The IgG Fc chain carries a single N-linked glycan which may undergo changes. Increased agalactosylated N-glycans are associated with rheumatoid arthritis (RA) and regarded as pro-inflammatory. Dysregulated neutrophils can make important contributions to host tissue damage. In RA, immune complexes (ICs) that have precipitated onto synovial joint surfaces activate neutrophils via Fc receptors, promoting localised inflammation. We engineered recombinant human monoclonal IgG with agalactosylated or galactosylated N-glycans, generated immobilised ICs and stimulated healthy donor and RA patient blood-derived neutrophils, comparing reactive oxygen species (ROS) production as read-out of neutrophilic inflammation. Both healthy donor and RA patient neutrophils generated less ROS when stimulated with ICs made from agalactosylated IgG. Mechanistically this was due to poorer binding of agalactosylated ICs to neutrophil Fc{gamma}Rs, causing lower activation of Akt and p38 MAPK. Both are required for immobilised IC-mediated stimulation of the neutrophil NADPH oxidase. Taken together, this suggests that disease-associated, agalactosylated IgG does not in fact promote inflammation and host tissue injury, at least not by acting on neutrophils. We propose that rather than promoting inflammation, agalactosylated IgG N-glycans that accompany inflammatory disease may arise as part of a compensatory mechanism that is aimed at reducing excessive inflammation and host tissue injury. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/735866v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@18a7178org.highwire.dtl.DTLVardef@1f8d75org.highwire.dtl.DTLVardef@1801a22org.highwire.dtl.DTLVardef@133e657_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2026

Leveraging TNFR2 for antitumour immunity: T reg depletion and myeloid reprogramming versus T cell costimulation

Although checkpoint inhibitors have revolutionized cancer treatment, responses are largely restricted to targeting CTLA-4 and PD-(L)1. TNFR2 has been identified as a target of interest, but a lack of understanding of whether agonists or blockers should be used, and whether Fc{gamma}R interactions promote effcacy, has hampered therapeutic antibody development. Here, we engineered two distinct -TNFR2 types: ligand-blocking Fc{gamma}R-engaging versus non-ligand-blocking agonist antibodies. Both showed potent anti-tumor effcacy across multiple syngeneic mouse tumor models and combined effectively with -PD-1. The ligand-blocking antibody depleted intratumoral T regs and reprogrammed the myeloid compartment, directing monocytes towards a pro-inflammatory macrophage and dendritic cell trajectory. Surprisingly, this effect depended on both inhibitory and activating Fc{gamma}Rs. In contrast, the agonist directly co-stimulated T and NK cells, through partially Fc{gamma}R-independent mechanisms. Both antibodies converged on activating tumor-specific CD8+ T cells mediating tumor rejection. Clinical assessment of both ligand-blocking (BI-1808) and agonist (BI-1910) -TNFR2 antibodies is currently ongoing. Graphical abstractO_LILigand-blocking anti-TNFR2 mAbs (BI-1808 and 3F10) deplete CCR8+ T regs and activate myeloid cells, remodeling the TME and leading to CD8+ T cell killing of cancer cells. T reg depletion and myeloid activation are mediated through interaction with activating Fc{gamma}Rs and the inhibitory Fc{gamma}RIIB, respectively. C_LIO_LIAgonist anti-TNFR2 mAbs (BI-1910 and 5A05) intrinsically agonize TNFR2 on T cells and NK cells, which is enhanced by Fc{gamma}RIIB crosslinking. The resulting broad lymphocyte activation mediates cancer cell killing. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/697572v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@3ecc17org.highwire.dtl.DTLVardef@c936a7org.highwire.dtl.DTLVardef@23189aorg.highwire.dtl.DTLVardef@243a05_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Deletion or Targeted Blockade of FcγRIIb (CD32b) Impairs α-Syn Propagation In-Vivo

Parkinsons disease (PD), the most common neurodegenerative movement disorder, is characterised by pervasive deposition of alpha-synuclein (-Syn) aggregates and the death of dopaminergic neurons. Fc gamma receptor IIb (Fc{gamma}RIIb or CD32b), the sole inhibitory Fc{gamma}R in humans (h) and mice (m), serves as a molecular conduit for intercellular -Syn transmission in-vitro. Here, we demonstrate that Fc{gamma}RIIb facilitates -Syn propagation and neurotoxicity in-vivo using the pre-formed fibril (PFF) -Syn model in mice. Genetic ablation of mFc{gamma}RII attenuated PFF -Syn-induced Lewy pathology, dampened associated neuroinflammatory responses, and preserved nigrostriatal dopaminergic neurons. Furthermore, pharmacological blockade of hFc{gamma}RIIb using clinically-related monoclonal antibodies mitigated acute-phase -Syn pathology in hFc{gamma}RIIb-transgenic mice following PFF challenge. Collectively, our results indicate that Fc{gamma}RIIb is a mediator of -Syn propagation in-vivo and highlight it as a tractable therapeutic target against -synucleinopathies like PD.

neuroscience↗

bioRxiv2024

Fc immunoreceptors promote autophagy to regulate monocyte functions

Receptors for the Fc fragment of immunoglobulin G (FcyRs) are critical in the defense against pathogens and in monoclonal antibody-based therapies. When activated by immune complexes or opsonized particles, FcyRs are endocytosed. Components of the endocytosis machinery are used during autophagy, a process which is triggered by starvation or by activation of specific receptors. In this work, we demonstrate that activation of FcyRs initiates autophagy, characterized by formation of p62 protein puncta and activation of ULK1, a major component of the autophagy initiation complex. Autophagy induction downstream of FcyRs activation involves the protein phosphatase Pp2a and its enzymatic activity, as demonstrated by in situ protein labeling. In animal models in which autophagy was inactivated or enhanced in myeloid cells, autophagy negatively regulates pro-inflammatory cytokine production downstream of FcyRs receptors, while being required for FcyRs -mediated antibody-induced cell phagocytosis and myeloid cell survival. Our results suggest that, for antibody-based therapeutic strategies that target the activation of FcyRs, an additional level of control can be obtained by manipulation of autophagy.

cell biology↗